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Sunday, 30. March 2014 13:33 Age: 8 yrs

Dynamic relaxation of a levitated nanoparticle from a non-equilibrium steady state

Category: Scientific Highlights

Published in Nature Nanotechnology

ABSTRACT:

Fluctuation theorems are a generalization of thermodynamics on small scales and provide the tools to characterize the fluctuations of thermodynamic quantities in non-equilibrium nanoscale systems. They are particularly important for understanding irreversibility and the second law in fundamental chemical and biological processes that are actively driven, thus operating far from thermal equilibrium. Here, we apply the framework of fluctuation theorems to investigate the important case of a system relaxing from a non-equilibrium state towards equilibrium. Using a vacuum-trapped nanoparticle, we demonstrate experimentally the validity of a fluctuation theorem for the relative entropy change occurring during relaxation from a non-equilibrium steady state. The platform established here allows non-equilibrium fluctuation theorems to be studied experimentally for arbitrary steady states and can be extended to investigate quantum fluctuation theorems as well as systems that do not obey detailed balance.

 

Figure: Experimental set-up. A nanoparticle is trapped by a tightly
focused laser beam in high vacuum. In a first experiment, the nanoparticle is
initially cooled by parametric feedback. At time t¼toff, the feedback is
switched off and the nanoparticle trajectory is followed as it relaxes to
equilibrium. After relaxation, the feedback is switched on again and the
experiment is repeated. In a second experiment, the nanoparticle is initially
excited by an external modulation of frequency Vmod in addition to feedback
cooling. Again at a time t¼toff, both the feedback and the external
modulation are switched off and the nanoparticle is monitored as it relaxes.

Gieseler J., Quidant R., Dellago C., Novotny L. (2014), Dynamic relaxation of a levitated nanoparticle from a non-equilibrium steady state, Nat Nano advance online publicationDOI:10.1038/nnano.2014.40

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